1. Technical Field
This invention relates to field harvesting machines for onions, and especially to machines for removing onion tops.
2. Background Art
Some of the difficulties in bulk harvesting of onions include:
1. Maneuverability of the harvester machinery in the onion field;
2. Adaptability of the machinery to green, or wet, tops, and to onions of varying sizes;
3. Capacity of the machinery, and
4. Ability of the machinery to prevent damage to the onions.
The University of Idaho, College of Agriculture, Bulletin 526 (May, 1971) discloses 9 approaches to onion harvester design, including an Air-Flo Harvester (Table, p. 4).
U.S. Pat. No. 2,553,519 (Lenz) discloses an onion topper in which an air stream lifts the onion tops on a horizontal portion of an open flight conveyor where a reciprocating sickle blade cuts the lifted onion tops. In this reference, the fan 62 is shown in the drawings to be directly underneath the horizontal portion of the conveyor, and is recited in both claims to be vertically axised and mounted between the spaced portions of the conveyor runs. At column 5, lines 17-20, however, this reference states that it is not essential for the fan to be mounted close to the top run of the conveyor.
My experience with the onion topper design disclosed in U.S. Pat. No. 2,553,519 is that debris in the form of stones, sticks and clods of dirt fall through the conveyor and onto the rotating blades of the fan, damaging the blades. Also, the air stream at the horizontal portion of the conveyor immediately above the fan is not uniform, resulting in uneven cutting of onion tops.
Therefore, there is still a need in the onion harvesting field for an air stream machine which is not susceptible to fan blade damage from debris, and which is able to uniformly cut onion tops.